Much has been made of President Barack Obama‘s decision to vote in favor of a U.N. Security Council resolution authorizing the International Criminal Court to investigate into possible crimes against humanity in Libya, an unprecedented show of support for the Hague-based tribunal by an American president.

But U.S. policy on the court had already undergone a major conversion since the days when John R. Bolton proudly reversed the Clinton Administration’s decision to sign the treaty establish the court, and President George W. Bush‘s U.N. envoy, John Negroponte, threatened to shut down U.N. peace-keepings missions in Bosnia and elsewhere in order to compel the UN to shield American soldiers from possible prosecution.

In her book Fighting for Darfur, Rebecca Hamilton provides an insider account into how the Bush Administration came to protect the court’s prosecutor, Luis Moreno Ocampo, from one of his greatest challenges: a movement by African states to prod the Security Council into suspending the prosecutors case against Omar Hassan al-Bashir.

In September 2004, U.S. Secretary of State Colin Powell had declared that the Sudanese government had committed genocide in Darfur, making the United States the first country to accuse Sudan of the worst possible act of mass killing. But they had no intention of giving the Hague-based court a shot at prosecuting it.

Bush’s point man for war crimes, Pierre Richard Prosper, launched a diplomatic campaign to establish an ad-hoc court to prosecute accused Sudanese war criminals. But the diplomatic push foundered, forcing the U.S. to acquiesce to a European initiative, led by France’s former U.N. ambassador, Jean-Marc de La Sabliere, in the U.N. Security Council to authorize the international criminal court to carry out an investigation. At the time, few expected Moreno Ocampo’s investigation to name President Bashir, a sitting head of state.

President Bush’s top Sudan envoy, Richard Williamson, once privately appealed to Moreno-Ocampo not to pursue genocide charges against President Bashir and then scolded him once he had gone ahead and done it."I said to Luis you have done the one thing no one else in the world could have done-united that African Union behind Bashir!"Williamson told Hamilton.

The decision triggered an immediate campaign by the African Union and the Arab League to call on the Security Council to defer the prosecution, invoking Article 16 of the Rome Statue, which created the ICC. The provision allows the council to suspend an investigation or prosecution for one year intervals if there is reason to believe the delay could help advance a peace process.

But Williamson had a change of heart. In a face-to-face meeting with President Bush, Williamson urged the president to grant him the authority to warn foreign leaders that the U.S. would veto any decision to suspend the ICC prosecution."Let me use the big V word?" Williamson recalled telling Bush,Hamilton writes ."You were the first world leader to call it genocide..you allowed the referral to go forward, and now the prosecutor has taken that and is seeking an arrest warrant for Bashir on the basis of him being a genocidaire. Do you really want to undermine that?"